Kindly answer the (b) part question
Solution
b. In case of Young double slit experiment, the sources must be coherent having same amplitude, same frequency and constant phase difference. Now when the student shifts the source such that it is slightly above the perpendicular bisector, then the intensity of light in both slits (S1 and S2) are no more remains the same. And the phase difference also changed due to unequal path difference in between the source and slits. Thus we will not get a sustainable interference pattern in this case.
b. In case of Young double slit experiment, the sources must be coherent having same amplitude, same frequency and constant phase difference. Now when the student shifts the source such that it is slightly above the perpendicular bisector, then the intensity of light in both slits (S1 and S2) are no more remains the same. And the phase difference also changed due to unequal path difference in between the source and slits. Thus we will not get a sustainable interference pattern in this case.